US Representative Edward J. Markey, the Democratic nominee for the US Senate, paid an effective tax rate of less than 20 percent over the past eight years, claiming large deductions for his mortgages, his travel expenses, and his car, his tax returns show.

According to his federal and state tax filings dating back to 2005, almost of all of Markey’s income, which ranged from $140,777 to $161,433 per year over the eight-year period, came from his congressional salary.

Markey, who turned 66 in July, also began collecting Social Security benefits last year, his 2012 tax return shows. The documents indicate he received $11,600 in Social Security benefits.

But Markey also wrote off large payments for mortgage interest, property taxes, and business expenses, in itemized deductions that ranged from a low of $38,378 to a high of $49,066 a year.